Phil Marshall Tolaga Research Papers

Over seven years ago, Shlomo Rakib, an engineer who has founded several wireless companies and even helped invent a new modulation scheme, attended a lecture about an unusual branch of algebra known as representation math. He became intrigued with the idea of applying the subject to wireless technology and signal processing, which had seldom been done before.

“It just clicked. It completely turned upside down everything we knew about wireless at the time,” Rakib says. His instinct was so strong that he founded a new startup company with the mathematician who gave the lecture, Ronny Hadani, an associate professor of mathematics at the University of Texas at Austin. The company, Cohere Technologies, is now vying for its place in fifth-generation, or 5G, wireless technology.

Cohere claims to have devised a more efficient air interface for 5G networks. Their new modulation scheme uses both time and frequency data about wireless channels to alleviate signal fading and multipath noise. The result, the company claims, is networks with higher capacity and stronger reception at the network edge.

Their technology, Orthogonal Time Frequency and Space (OTFS), captures accurate data about wireless channels that, when combined with algorithms, can help compensate for distortion, interference, and other wireless handcuffs. The technology also combats the Doppler effect in mobile applications, such as the antennas embedded in smartphones and that could find their way into autonomous cars.

In recent field tests, the company says that OFTS modulation enabled “perfect linear scaling” of multiple-input multiple-output (MIMO) radios, which are expected to be a major component of 5G networks. MIMO links together multiple transmit and receive antennas to increase network capacity. But adding more antennas to the array has been difficult without introducing more signal fading and interference.

“From a technical perspective, the approach makes sense,” says Phil Marshall, an analyst with Tolaga Research, a wireless research firm. “There is a great deal of value that can be garnered from techniques that capitalize on the time and frequency domain diversity of wireless channels.”

Rakib, Cohere's chief executive, claims that existing technology too often has high overhead for accessing a wireless channel. OFTS technology spends only 0.15% of the network’s capacity to acquire a wireless channel, whereas today’s modulation schemes require about 7% overhead per stream.

Larger companies like Qualcomm, Huawei, and Alcatel-Lucent have been tweaking OFDM, the modulation scheme that defines 4G technology, to meet new 5G requirements. But Cohere Technologies claims that their technology sits on top of OFDM. It preserves what works with OFDM—high spectral efficiency and multipath noise canceling—while also bolstering capacity, coverage, and data rates.

Overlaying instead of replacing OFDM could be a major benefit as the standards process for 5G moves forward. The 3G Partnership Project (3GPP), the standards group overseeing 5G standards, has the task of sorting through new air interfaces, wireless chips, and other technologies from research labs and universities.

Rakib says that the other new interfaces are not a significant departure from the OFDM waveform. Nokia, Alcatel-Lucent, and others have designed a filter band modulation, while Qualcomm is developing another approach. Huawei and others are promoting a sparse code multiple access approach and have even tested the technology in China.

At this point, it is difficult to predict what approach will make it into 5G. Rakib suggests that these plans will eventually consolidate around one main proposal. But he thinks it will not be until around 2018 that the 3GPP agrees on one. If OFTS technology gets into the new standard, Cohere will be able to license it to other companies.

In the view of industry analysts, time is not on the company's side. “Like any startup, Cohere will face sustainability challenges during a long technology acceptance cycle,” says Ken Rehbehn, an analyst with 451 Research, in a research note. In the next few years, new advances could "dull the luster" of its new modulation scheme, he said.

For now, Cohere still has a certain luster. In three rounds of venture capital funding, the company has raised around $90 million with investments from Telstra, an Australian telecommunications company, and other technology investors like Lightspeed Ventures and New Enterprise Associates.

With the 5G standards process in its early stages, the company is hedging its bets with new equipment based on OFTS. The new equipment is designed to be “a wireless extension of fiber” with an eye toward delivering 1 gigabit wireless service, presumably to enhance current LTE networks. The company is also preparing MIMO radios with 64 × 64 antenna arrays.

Even with all their technology in the works, Rehbehn is not certain of the end game for Cohere. “Is this an intellectual property firm like InterDigital? Is it a silicon supplier like Qualcomm? It is too early to tell, but Cohere’s intellectual assets are attractive and should set the stage for an interesting journey.”

To help us find some answers, we asked Phil Marshall, Chief Research Officer at Tolaga Research to share his insights.

“Operators need to continue to advance the network to meet the tremendous growth in demand,” Marshall says. “There are three key areas – ultra-broadband, low latency connectivity and ultra-reliable services. While the demand for ultra-broadband is well understood, it’s harder to predict the need for low latency and ultra-reliability. How quickly will virtual reality and augmented reality take hold? When will autonomous vehicles be adopted and how will it be implemented? These are uncertainties that can be addressed by building pockets of capabilities, which can scale up flexibly to support these services where they are needed.”

Fragmentation is happening now says Marshall: “In the short to medium term, we need to anticipate growing fragmentation and move past the traditional concept of one large network, to a model where targeted capabilities are deployed in specific places for subscribers. The move towards 5G has a focus towards localized campus areas, for example to support Industry 4.0 or along highways to provide automotive connectivity.”

Another issue Marshall pinpoints is the growing difficulties of finding real estate on which to deploy the infrastructure needed to meet demand. The real estate squeeze can be addressed by “small cells, which represent a change in strategies for getting infrastructure in the right places, while a focus on partnerships and network sharing will be needed,” Marshall says.

Cloud RAN and edge will converge

Serving local demand will depend heavily on Multi-access Edge Computing (MEC), which Marshall says is a key part of the shift from traditional approaches and an essential component of future 5G networks. MEC places cloud computing capabilities at the edge of the network, close to the users to enable the delivery of ultra-low latency, very high throughput and locally-relevant services.

“I am bullish on the need to distribute resources to the edge. Future-proofing the network depends on an understanding of how distributed computing will evolve over time. Many operators are emphasizing the use of MEC to augment network architecture and drive new revenues,” explains Marshall.

“We also need to push the boundaries of antenna technology, as well as understand the overall economics of macro infrastructure, small cells and Cloud RAN. To optimize resources, it’s a challenging equation to balance.”

Marshall sees cloud technologies as being crucial, with Network Functions Virtualization (NFV) and Software Defined Networking (SDN) being catalysts for operational change. The result will be a move away from focusing on managing complexity to the use of IT technology and automation to abstract complexity and simplify operations. The communications industry should aim to leapfrog the IT world “to develop virtualization technology for the network environment, particularly through container-based architectures. Such changes are significant from an operational standpoint, particularly for operators that continue to maintain legacy regimes. This is not a good thing and operational transformation is crucial,” he explains.

5G will enable greater innovation

5G will enable leapfrogging advances, believes Marshall. “In reality, operators are not going to migrate their entire network to container-based web-native infrastructure any time soon. However, 5G will manifest itself in local initiatives, where disruptive change can be incubated. Operators can experiment without creating a disaster if things don’t work out – it’s about having flexibility and 5G provides a means for doing that.”

Marshall also says that deploying Cloud RAN will be essential for 5G end-to-end network slicing to support specific services. Cloud capabilities are already established in the core network and are now pushing out to the edge of the network. But he sees challenges: “Network engineers are not always IT savvy. Many see cloud technologies as being unreliable and incompatible with their operations. This is where Nokia’s expert services can provide the competency to help operators make the transition, to incubate these solutions into the network with low risk. A good example is the work Nokia is doing in edge computing and its collaboration with Amazon Web Services Greengrass. It’s not about driving operators along a set trajectory, but about how to incubate change and where the opportunities are.”

Another technology central to future 5G networks is mmWave radio. “mmWave is a wild card. If we put the technology into urban environments, we can create massive capacity and offload traffic from conventional networks – there could be some strong economic drivers for mmWave, particularly if advanced radio systems are developed to address coverage challenges” he says.

For Marshall, the most important message he has about 5G for operators is to “take a local and focused approach. Don’t treat it as 4G. Use it as a platform for change as you can go in all kinds of different directions from here.”

What did we learn?

Here’s what we consider as the key take aways fromMarshall’s insights:The real estate issue means a change from traditional architecture with more deployment of small cells and making greater use of existing sites with compact, highly efficient base station solutions.

And clearly, Cloud RAN and MEC deployment will be critical for providing the low-latency, high-throughput needed to capture new revenue from demanding new services, whether on the road or in venues and industrial sites.

Flexibility is needed to scale up and meet unpredictable demand and the uncertainties of how quickly new services and applications will be adopted. This calls for infrastructure and operations that take advantage of virtualization, as well as advanced antenna technology.

And of course, 5G is always part of the equation. Deploying 5G-ready infrastructure that can run all radio technologies, including mmWave, is essential to give operators the flexibility to try out new services and evolve to a network that will provide the ultra-broadband capacity so essential to meet future demand.